1. Field of the Invention
The present invention relates to polymers useful in achieving oil and water separation and water clarification. The present invention particularly relates to such polymers that are copolymers.
2. Description of the Prior Art
Chemical demulsification is a convenient and effective method in breaking water in crude oil emulsions. Demulsification may be important in the production of oil and gas for several reasons. One reason is because in the normal course of producing the oil and gas from a subterranean formation, at some point significant amounts of water may be co-produced with the oil and gas. When the water is co-produced as an emulsion, it is usually necessary to break the emulsion prior to transporting the oil to market.
The emulsion may be a natural emulsion due to the presence of naturally occurring emulsifying agents, or the emulsion may be an artifact of the use of additives or recovery processes. For example, the use of steam and caustic injection or combustion processes, for in-situ recovery of heavy oils, may be complicated by the production of viscous emulsions of oil, water and clay. Crude oil is found in the reservoir in association with gas and saline or fresh formation water. A natural emulsion may form simply due to shear and pressure drops at the well head, chokes and valves.
One chemical solution to the problem of emulsification is disclosed in U.S. Pat. No. 5,100,582 to Bhattacharyya. This reference discloses polymeric demulsifiers for breaking water-in-oil emulsions having random structures prepared using varying percentages of acrylic acid, methacrylic acid, ethyl hexyl acrylate, monomethyl acrylate and butyl acrylate as their effective constituents.
Considerable expenditures are made each year for water treatment applications, such as coagulants and flocculants used to clarify raw waters for potable and industrial use. One such application is to clarify process water streams such as water in paper recycling plants and mining wash water circuits. Another application is for clarification of industrial and municipal effluent waters.
One approach to such clarification applications is disclosed in U.S. Pat. No. 6,190,561 to Nagan, in which it is disclosed that a zeolite crystalloid coagulant prepared by using aqueous sodium silicate and sodium aluminate solutions can be used to clarify water by coagulating particulates.
Another solution is disclosed in U.S. Pat. No. 6,025,426 to Hurlock. Therein, hydrophilic cationic copolymers of acrylamide having high molecular weights are disclosed to be useful as raw water clarification aids, emulsion breakers and waste water clarification aids.